On Monday, the 300,000 residents of nine counties in West Virginia were told that they could resume drinking and using their tap water, five days after an estimated 5,000 gallons of the chemical 4-methylcyclohexane methanol (MCMH) leaked into the Elk River near Charleston.

As National Geographic previously reported, MCMH is used as a foaming agent to wash certain types of coal before it is sent to market. The chemical leaked from a 48,000-gallon storage tank owned by Freedom Industries, located about a mile upriver from a drinking water treatment plant operated by West Virginia American Water, affecting the central and southwestern parts of the state.

Working with state officials, the utility lifted the ban on drinking water gradually in the region on Monday, so the system would not be overwhelmed by demand. Customers were asked to flush out their water pipes before using any of the water. The utility said the water could still have a faint odor or taste for some time, but that it was considered safe.

However, Sonya Lunder, a research analyst with the Environmental Working Group in Washington, D.C., told National Geographic that the decision to lift the water ban was based on scant science. "Evidently the one-part-per-million safety level, used to lift the drinking water restriction, is based on an unpublished study of the amount of chemical that killed 50 percent of test animals, a very crude indicator of health concern," she said.

View Images

Public works employees in South Charleston, West Virginia, assist local residents in obtaining bottled water on January 12, 2014.

PHOTOGRAPH BY MICHAEL SWITZER, DESIGNWORKS VIA AP

Spill's Ecological Effects?

Lunder added that there are unanswered questions about the spill's possible ecological impacts, from a chemical that "most people had never heard of."

Lunder said she reviewed the official material safety data sheets for MCMH. "They say things like the chemical could be irritating to skin and eyes and that you should try to keep it from getting into waterways, but these are typical emergency measures and they're not always based on data," she said.

Lunder also reviewed the scientific literature, and she said that there doesn't seem to be any publicly available studies on what the impacts of the chemical would be to either human beings or wildlife, or how long the chemical will persist in the environment. "There's little data with which to draw any conclusions on what effects might be," she said.

Brian Lutz, a biogeochemist who studies the environmental impacts of the coal industry at Kent State University in Ohio, said,

The lack of toxicological data on MCMH is staggering.

He added: "While I'm unaware of any spill of this chemical in the past, there have been multiple high-profile cases in the past in which slurry impoundments—structures holding the residue from coal washing and preparation—have failed. Because of this, it seems reasonable to expect that we should have detailed information available for all chemicals used to prepare coal."

Lunder said it appears that companies did report some production information on the chemical to the Environmental Protection Agency (EPA) in 2011, but that "it was kept confidential." Calls for comment to the EPA and the West Virginia Department of Environmental Protection have not been returned.

Lunder added that 4-methylcyclohexane methanol does not appear to be very volatile, so it is unlikely to evaporate quickly. "But how long it will take to break down is unclear," she said.

Lutz added that it's possible the chemical was quickly diluted once it reached the larger Kanawha River from the smaller Elk River, although he noted that it is hard to know, given the lack of toxicological data.

Lunder pointed out that the chemical was already on the market in 1976, when Congress passed the Toxic Substances Control Act. "Screening of new chemicals would have looked at those questions, but the government did not look at what was already on the market because there was political pressure and because there were so many chemicals already out there," she said.

Asked if the spill likely does pose a threat to downstream communities or to living things, Lunder said it is unclear, although she said the chemical isn't that acutely toxic. "If it had been 5,000 gallons of dioxin, a persistent and highly toxic chemical, it would have been terrible," she said.

What the Chemical Is Used For

An industrial chemical, 4-methylcyclohexane methanol is used at about 20 to 25 percent of coal processing plants in West Virginia. It is used in a process called froth flotation, which separates sand-size particles of coal from the surrounding rock, in a tank of water or another solution.

It is used primarily to produce coal for metallurgical purposes, so-called coking coal. It is rarely applied to coal that is burned to create electricity, so-called steam coal, which represents the vast majority of coal produced.

Lutz added that although some people may view the spill as an isolated incident, "the people of Charleston and surrounding areas are now unfortunately experiencing the same concerns that have plagued many people throughout rural West Virginia. Coal mining, especially mountaintop removal, has had severe and widespread impacts on water resources throughout the region."

Lutz said the spill may serve as an "opportunity to revisit and improve laws and regulations protecting water resources—both in Charleston, as well as throughout the rest of the state."